Technology for teleconference through a network is proposed. For example, a Web conference system is disclosed. The Web conference system includes a Web conference server, an LDAP server, and a plurality of client terminals. The Web conference server performs communication with the LDAP server and the plurality of client terminals through a local area network. The Web conference server manages a user management table. The LDAP server is a server that provides a directory service for connecting by an LDAP protocol. The LDAP server manages personal information in a centralized manner. In the Web conference system, authentication for general users is performed by using user information managed by the LDAP server. Authentication for guest users is performed by using user information managed by the Web conference system.